I am really interested to build a trial. Yet, there are different grades in dual jfet J109/K389 - GR,BL,V. I can find GR and V but not BL in the market. May I know what are the needs to use different grades of J109/K389 in this circut?

first - if you're not aware of importance and reason why different current grade parts are used , maybe you aren't ready to construct your own ; there are more than enough informations for little reverse engineering/constructing ...... but you must know basics
second - I can't find anywhere in text that 109/389 are used at all ..... even if I know that already .
are you sure your informations are from that pdf ?
third - Papa Borbely choose to not reveal publicly all circuit details ..... so I'm pretty sure that no-one will help you in that , at least in public forum

click on CookBook link in my signature . there you'll find one similar shunt reg , with all necessary details of construction ; feel free to build it

I know he is using dual Jfet J109BL/K389BL because my brother just bought one. He is a very serious DIYer but I'm not - just loved to use a solder gun and make something for my non-serious use. Erno put his circuit and description on his web therefore I think he is open for people to build his design.

I believe there could be fake 109/389 in the market but actually, I can only find 2nd hand 109/389 V grade in China (Shenzhen Electronic City). I don't know would people make fake 109/389 and sell as second hand components?

I believe there could be fake 109/389 in the market but actually, I can only find 2nd hand 109/389 V grade in China (Shenzhen Electronic City). I don't know would people make fake 109/389 and sell as second hand components?

By the way, are your BL grades new or used? How many pairs you have?

What price are you getting these V grade Fets? You can check IDSS using known method to check. IF they behave like a fet they cannot be fakes. Used ones are better as they are possibly genuine
kannan

With the exception of CCS, the Op-Amp shunt is very similar to the one I'm using here: The Phono Stage

It is indeed very good sounding regulator, way better than all 3pin types I tried.

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Mine were bought years ago when they were still available, from reliable sources, and I have tested them all. So I am sorry to say I am not prepared to trade them for second hands from Shenzhen. If you need BL grade, I suggest you buy matched pairs of 2SK170BL / 2SJ74BL and use e.g. my Dual JFET heatsink (see thread below).

You can test them according to Borbely's article. And I think I have described my testing method somewhere, e.g. :

I am getting the second hand 109/389 at about US$8 each pair, grade V, tested (as alleged) in Shenzhen. I did not buy them last week but I think I should have because the cost of time and traveling makes it worth to buy a few pairs to play with.

My brother tried a number of power regulators for his phono amp - DACT CT-100, Erno Shunt Regulator, 3-pin, Op-amp shunt and BJT shunt. So far, the DACT and Erno's are very close. DACT has more punch while Erno's is very musical but lack the power of DACT. It is difficult to choose between these two.

Peter, I don't know my brother went to Toronto with his phono amp in October. Otherwise, I will ask him to contact you and have fun with his toy.

I will try to build this regulator with multi-purpose PCB and see how it works with my DACT phono.